Metal-oxide based thin-film transistors (TFTs) have received much attention as replacements for silicon-based TFTs in display applications. The advantages of using metal-oxide based TFTs over their silicon-based counterparts are many: including transparency, high on/off current ratio, high carrier mobility, low off leakage current, and relatively low processing temperature.
However, a high density of defects—including native defects (oxygen vacancies, zinc interstitials), dangling bonds, and grain boundaries—are present in commonly-used metal-oxide semiconductors, and TFTs built on such defective material exhibit poor sub-threshold slope, instability and performance non-uniformity. Thus, there exists a need to reduce the density of defects for metal-oxide based TFTs.